Workholder and method for internal grinding



A ril 25, 1961 c. J. TERP 2,931,037

WORKHQLDER AND METHOD FOR INTERNAL GRINDING Filed April 17, 1958 2 Sheets-Sheet 1 IN VENTOR ATTORNEYS C. J. TERP April 25, 1961 WORKHOLDER AND METHOD FOR INTERNAL GRINDING Filed April 17, 1.958

INVENTOR CkarIeJJYIp ATTORNEYS WORKHOLDER AND METHOD FOR INTERNAL GRINDING fiharles J. Terp, Springfield, Vt., assignor to Bryant Chucking Grinder Company Filed Apr. 17, 1958, Ser. No. 729,126

10 Claims. c1. 51-237 This invention relates. to a workholder for holding one or more workpieces for internal grinding, and the workholder of this invention has particular utility in holding workpieces having irregular or intricate outside configurations for automatic handling and grinding in an internal grinding machine.

When grinding holes in parts having irregular, andfrequently intricate outside configurations, the manufacturer is often faced with the necessity of procuring special workholding devices at high initial cost, and such devices are often cumbersome to use andrarely lend themselves for utilization in automatic machine processing. This is particularly the case in the manufacturing of sundry parts for office and accounting machines, calculators, cash registers and the like, where the unit cost of these parts is very critical. The office machine manufacturers and others desire and need economical workholding devices adaptable for use in modern high production automatic internal grinding machines.

It is therefore an object of this invention to provide a novel workholder adapted to accept workpieces of intricate and irregular, as well as plain outside configurations, and to hold these workpieces in a manner such that a hole may be generated therein concentric with a predetermined reference surface or points.

Another object is to provide a workholder suitable for use in connection with automatic loading devices of internal grinders.

A further object is to provide a workholder that in its simplicity of structure is economically justified for small lot manufacturing.

With the above and related objects in view the invention will be found in certain novel features of combinations and subcombinations, which will more fully appear from the following detailed description, taken in connec tion with the accompanying drawings illustrating a preferred embodiment in which: a

United States Patent i 2,981,037 Patented Apr. 25, 1961 26 on their perimeters acting as retaining means in combination with spring actuated pins 16 spaced angularly 120 as shown in Fig. 2.

The central bores and counterbores or internal cavities in the bodies, and pressure plates are made in various sizes and are shaped to accommodate and locate sundry and different workpieces. For example, body 11 is shaped to accommodate two spur gears 41 having hubs.

The gear teeth cooperate with pins 19 and to locate the axis of the workpiece coincident with the axis of the body of the shuttle. Body 21 will accommodate a single ratchet wheel 51 with a hub, and the outside diameter of this hub, by being piloted in the central hole of the body, constitutes the locating means. Body 31 will accommodate six ratchet wheels 61 in the form of thin annular disks, which are, for locating purposes, piloted on their outside perimeter by a portion of the counterbore of the body 31. The bodies 11, 21 and 31 all have the same diameter peripheral portion 10 and all have a face 13 normal to the axis thereof. The counterbores 15 terminate in shoulders 17, 27 and 37 respectively, which shoulders are parallel to the face 13. It will be clear that the distance between these shoulders and the face 13 may be varied in different shuttles to suitably locate a particular workpiece in correct longitudinal position relative to face 13. v

Fig. 3 illustrates the use of the principles of the invention to hold a workpiece or workpieces having relatively plain outside configurations. The shuttles 'of Fig. 3 are adapted to hold the matching inner and outer races 205 and 203 respectively of a ball bearing. Race 205 is supported in the counterbored body 200 of a shuttlehaving a predetermined outside perimeter 210 and a normal end face 213. A pressure plate 212 is utilized with detent means 16 and 26 to hold the workpiece in the shuttle during handling. A radial spacer support 209 is positioned between the race 205.and the counter- Fig. 1 is a series of workholders of the invention shown in cross-sectional elevational views;

Fig. 2 is a plan view of a workholder in Fig. I viewed from the right;

Fig. 3 is a side sectional elevation view showing a pair of workholders for holding the inner and outer races of a ball bearing;

Fig. 4 is in general the same as Fig. 2 on an enlarged scale, and with the pressure plate removed for clarity; and

Fig. 5 is a side sectional elevation of the workholder shown in Fig. 4 but with the pressure plate replaced.

In Fig.1 there is shown three workholders of the invention, hereinafter called shuttles. These shuttles have annular bodies 11, 21 and 31 respectively, of the same outside diameter and width. The bodies each have a central bore, which is enlarged by a counterbore 15 forming an internal cavity. In the counterbores are loosely fitted annular pressureplates 12, 22 and 32, re-

spectively. These pressure plates have parallel face porbored body. In a similar manner race 203 and backing spacer 211 are heldin the body 201 of the other shuttle, and a pressure plate 214 is similar in shape and purpose with the pressure plates previously described.

The manner of restraining sundry workpieces longitudinally and with their axes in coincidence with the axis of a shuttle is the same in principle, and differs only in the matter of choice of reference means, as is evident from the different adaptations illustrated in Fig. 1 and Fig. 3.

Figs. 4 and 5 are enlarged views of a shuttle adapted to be utilized for grinding a spur gear similar to that shown in the left shuttle of Fig. 1. In Fig. 4 the pressure plate 12 is removed, but it is shown in Fig. 5 in sectional elevation. This pressure plate has a continuous circular rim portion 26 which, together with the spring biased pins 16, act to form a detent to confine the pressure plate'v and prevent it from being separated from the assembly during handling of the shuttle when the shuttle is not. in operative position on the grinding machine. The

11. These pins protrude into the counterbore 15 and are.

radially and angularly spaced to be contacted by opposing gear tooth faces of gears 41, in a manner well known in the art underthe term pitch line control.

When supported in this manner these workpieces will be restrained from moving radially and will have their axis coincide with the axis of the peripheral surface 10 of" the body'll.

The shuttles are intended for use on internal grinding machines, particularly of the centric type, where a cit-" cular surface is generated about a support determined axis. A centric internal grinding machine can be defined as a machine for generating a surface of revolution about a support determined axis and where the rotation of the workpiece is controlled by the lateral engagement of a side, or sides, of said workpiece by a rotating member. An example of such a centric internal grinding machine is described in U.S. Patent No. 2,635,395 issued April 21, 1953, to Arms et al. Again referring to Figs. 4 and 5, there is shown the means for the radial support of the shuttle, by two angularly spaced shoes 1% and 101 in contact with the perimeter of the shuttle 11. A rotatable driver 102 with a face portion 103 normal to the axis of the driver axially supports the body 11 on its face 13 to drive the shuttle assembly while held in frictional relationship thereto. A freely rotatable clamp 1% with a face 107 in contact with the face 57 of the pressure plate 12 forces the face 47 towards the face 17 through the intermediary of the workpieces 41 and thereligsholds the entire shuttle assembly in contact with face The above mentioned grinding machine features are well known in the art and forming no part of the structure of the present invention will not be further described. However, one way to utilize the device of the invention would be in combination with a loading device described in my oo-pending application, Serial Number 670,698, filed July 9, 1957, now Patent No. 2,927,406, to which reference may be had. After a workpiece, or pieces, have been assembled in a shuttle, together with a pressure plate, the detent means will hold this shuttle assembly together so that it can be handled as a unit by the automatic workloading and ejecting equipment disclosed in my aforesaid application. In this way work can be handled and fed to the grinder in a safe, simple and fast manner compatible with the high capacity of modern automatic machines where the processing time is a matter of seconds. A further means of economy in tooling cost is exemplified in Fig. 1 where there is shown an adaptation for grinding three different workpieces having different outside configurations, but all requiring the same diameter holes to be generated therein. The shuttle with body 11 holds two workpieces 41, the shuttle with body 21 holds one workpiece 51, and the shuttle with body 31 holds six pieces 61. If we assume that a lot contains equal numbers of these different workpieces, and the machine cycle timing requires a minimum of ten shuttles to be kept in continuous operation, then by furnishing three shuttles for piece 41, six for piece 51, and one for piece 61, and serving the different shuttles intermixed at random to the loading chute, the aforesaid requirement is fulfilled in an economical way.

In cases of small lots processing where it is not economically justified to break into the regular lines of high production machines, the present invention may be adapted favorably, as exemplified in Fig. 3, wherein there is shown two shuttles with the same widths and same outside diameters, one made to accommodate an inner race 205 of a ball bearing in a body 200, and the other a matching outer race 203 in a body 201. It will be apparent that with the same predetermined dimensions of these bodies the shuttles may be made to accommodate a series of different sizes and forms of ball bearing races inside a reasonable range. With the conventional manner of grinding workpieces on a support determined axis the setup time for the work supports may exceed several times the actual productive processing time of a small lot, but by using a selected size series of shuttles this unproductive setup time is entirely eliminated.

From the foregoing description it will be evident to those skilled in the art that various changes and modifications of structure and as combinations may be made Without departing from the spirit and scope of the invention.

I claim:

1. A device for holding a workpiece which may have an irregular outside configuration for handling and grinding in a centric internal grinding machine of the type having a driving spindle with a work driving face normal to the rotative axis thereofand radial work supports determining the rotative axis of a workpiece, the device comprising; a portable annular body having a complete ly cylindrical predetermined outer periphery adapted to be frictionally contacted by the radial work supportsduring a grinding operation, one end -face of the body being normal to the axis thereof to be driven by the driving face of the driving spindle, the b'ody also having a workworkpiece held thereagainst to the driving face of the driving spindle, and means within the body for radially. referencing an annular workpiece held therein to thecylindrical periphery thereof and hence to the work supports, an annular pressure plate loosely contained with-' in the counterbore and adapted to retain a workpiece between its inner end face and the shoulder of the counterbore during handling thereof and adapted to axially and rigidly hold the workpiece in the body when an outside clamping force is applied to the normal end face and the pressure plate during the grinding operation, and detent means for holding the pressure plate within the counterbore.

2. A device as defined in claim 1 wherein the inner end face of the pressure plate contains a workpiece con tacting portion which is parallel to the outer end face thereof.

3. A device as'defined in claim 2 wherein the detent means comprise a plurality of spring projected pins directed inwardly into the counterbore from the body and cooperating with a rim on the perimeter of the pressure plate.

4. A device as defined in claim 3 further comprising a plurality of pins attached to the bodyand projecting axially into said counterbore, said pins being mounted on a circle whereby they may contact the gear teeth of at least one spur gear workpiece on the pitch line circle thereof to prevent radial movement of the gear relative to the body.

5. A device as defined in claim 3 wherein said counterbore is stepped down inwardly and the innermost step portion has a predetermined diameter for contacting the periphery of at least one annular workpiece adapted to be held'therein and thereby restrain any radial movement of the workpiece relative to the body.

6. In an internal grinding machine, of thecentric .type where a surface of revolution on a workpiece is generated about a support determined axis defined by cooperation between radial support means and a preformed circularsurface, and where a clamping force acts inanaxial direction to hold the workpiece in frictional relationship with a face portion normal to the axis of a rotatable-driver; a portable workholder shuttle assembly adapted to retain and locate at least one workpiece in predetermined radial and axial relationship to said support means-and said face portion respectively, the shuttle assembly comprising: a portable annular body having a completely cir-j cular smooth external perimeter adaptedto be. supported on said radial support means and said body being'an end face normal thereto, means defining an interior cavity provided with a shoulder portion parallel to said normal between said shoulder portion and said pressure plate through an intermediate workpiece and is the sole means for holding the shuttle assembly in frictional relationship against the face portion of the driver.

7. A device as defined in claim 6 wherein the body is provided with radially yieldable detent means projecting into said cavity to act as a snap lock for retaining and securing the pressure plate within the cavity, independently of said clamping force.

8. A method of workpiece handling and centric internal grinding to successively generate constant internal surfaces of revolution on workpieces having difierent outside configurations, the steps comprising: mounting the workpieces of different outside configuration in workholder shuttles having, independent of the said difi'erent configurations of the workpiece, outside circular perimeters of pie-established like diameters; placing the workholder shuttles successively with their perimeters held against radial support means of a centric grinding machine whilst said support is pro-adjusted to establish a single axis of revolution for the surfaces to be generated; and grinding the workpieces.

9. A method of workpiece handling and internal grinding utilizing a centric internal grinding machine to generate a constant internal surface of revolution in successive workpieces having different outside configuration, comprising; mounting the workpieces having different outside configurations in workholder shuttles, each of the workholder shuttles having an outside periphery of the same pie-established diameter and also having one end face normal to the outside periphery, loosely restraining each workpiece having a different outside configuration in each workholder shuttle by means within the shuttle to prevent the workpiece from separating from the shuttle during handling, placing the workholder shuttles at random and successively on radial support and axis determining means of a centric grinding machine so that the pre-established outside diameter of the workholder shuttle periphery rides on the radial support and axis determining means of the centric grinding machine to establish an axis of revolution for surfaces to be generated, rotating the workholder shuttle by frictional contact between the normal end face of the shuttle and a drive spindle of a centric grinding machine, axially clamping the shuttle against the drive spindle by a rotatable clamp, and grinding an internal surface of revolution in the workpiece so positioned by means of the centric internal grinding machine.

10. A method of workpiece handling for generating a constant internal surface of revolution in successive workpieces having diflerent outside configuration while utilizing a centric internal grinding machine, comprising; mounting each of the workpieces having the different outside configuration in a cavity in a workholder shuttle, there being a plurality of workholder shuttles, each of the workholder shuttles having an outside peripheral surface of pre-established diameter and one end face normal to the outside peripheral surface, radially restraining each workpiece in each workholder shuttle so that the axis of the workpiece coincides with the axis of the workholder shuttle, loosely axially restraining each workpiece having a different outside configuration in each workholder shuttle by a detented annular pressure plate within the cavity in the shuttle to prevent the workpiece from separating from the shuttle during handling, successively placing workholder shuttles chosen at random and containing workpieces having difierent outside configurations but in which the same internal surface of revolution is desired to be generated on radial support and axis determining means of a centric grinding machine so that the pre-established outside peripheral surface of the workholder rests on the radial support and axis determining means of the centric grinding machine to establish the axis of revolution for surfaces to be generated, rotating the workholder shuttle by frictional contact between the normal end face of the shuttle and a drive spindle of a centric grinding machine, clamping the shuttle against the drive spindle by a rotatable clamp acting axially on the annular pressure plate within the workpiece shuttle, and grinding an internal surface of revolution ina workpiece so positioned.

References Cited in the file of this patent UNITED STATES PATENTS 1,854,825 Connell Apr. 18, 1932 2,105,618 Silva Jan. 18, 1938 2,443,895 Day June 22, 1948 2,450,970 Lance Oct. 12, 1948 2,696,986 Grobey Dec. 14, 1954 2,706,369 Dix Apr. 19, 1955 2,754,641 Bidwell July 17, 1956 2,820,641 Garrison et a1. Jan. 21, 1958 2,885,212 Garrison et al. May 5, 1959 

